Self-regulating device for electromagnetic clippers



i v v1,626,058 Aprlll 26, 1927. J. WAHL SELF REGULATING I`)EVICE FORELECTROMAGNETI CLIPFERS Filed Oct. 16, 1925.

of iron will be at such a rate that the in` Patented Apr. 26, 17927.

UNITED STATES PATENT OFFICE.

LEO J'. WAHL, OF STERLING, ILLINOIS, ASSIGNOR TO WAHL CLIFPERCORPORATION,

OF STERLING, ILLINOIS, A CORPORATION OF ILLINOIS. y

SELF-REGULATING DEVICE FOR ELECTROMAGNETIC CLIPIERIS.

Application filed October 16, 1925.

My invention relates to a self-regulating device for regulating thepower'of electrolmagnetic clippers.

It is a purpose of my invention to provide means whereby the powerobtained from an electro-magnetic clipper is substantially uniform eventhough the voltage impressed 011 the electro-magnet varies. `This isaccomplished by providing a core that is unsymmetrical relative to thecoil of the electromagnet and means resisting movement of said coil inone direction so that an increase in the voltage of the energizingcurrent moves the coil against the resistance of said means to increasethe self-inductance thereoi', while a decrease in voltage will causesaid means to move the coil in the opposite direction to decrease theself-inductance, it being obvious that said means can be so adjustedthat the movement of the coil will be .such that the effect of thecha-ngev in self-inductance will counter-balance the effeet produced bythe change in voltage so that the power obtained from the electromagnetwill be substantially uniform.

More particularly it is a purpose oi' the invention to provide anelectro-magnet having a core extending through the coil thereof that hasa relatively large' mass of iron at one end of the core, the coi] beingmovable on the core toward and away from said end having the large massof iron and to provide resilient means counteracting the movement of thecoil toward the larger mass of iron to thus provide substantiallyuniform power obtainable from the electromagnet. It is well known thatwhen the voltage increases, the tendency of the coil to move furtheronto the 4core toward the large mass of iron will increase. By adjustingthe tension of the resilient means, this tendency can be counteracted insuch a way that the movement toward the larger mass crease inself-inductance brought about by the approach of the coil toward thelarge mass of iron will be just enough to decrease the power of theelectro-magnet as much as the increase in voltage wouldyotherwise haveincreased the power ot said electro-magnet, thus providing anelectro-magnet` that has substantially uniform power. This is quiteimportant in view of the fact that the voltage varies considerably onthe lines of centr'al station systems. If the voltage in- Serial No.62,806.

creases, and the power becomes too great, the armature will be drawnagainst the core or against a suitable stopmember with such force as t oproduce a chattering of the clipper. Wvhlle if the 'device is soadjusted that this will not occur when an increase in voltage takesplace, the normal voltage will be insufficient to etliciently operatethe movable blade of the clipper. Preferably, the mass of lron 1sprovided by a cross piece on the core which also serves the function ofproviding` a path for the magnetic flux from the central portion of thecore at the one end of the coil toward the movable element or armature.

The arrangement whereby the power of the electro-magnet is adjusted dueto the movement of the coil on the core is of great advantage over themethods previously used due to the fact that such methods usuallyconstituted movement of the armature relative to the core to vary thegap between the core and the armature which resulted in undue heating ofthe electro-magnet upon an increase in voltage, as the magneticresistance was also increased simultaneously with the increase involtage.

Other objects and advantages of the invention will appear as thedescription of the accompanying drawings proceeds. However, I desire tohave it distinctly under# stood that I dol not intend to limit myself tothe exact details shown or described, but that I intend to include aspart of my invention all such obvious changes and modifications of partsas would occur to a person skilled in this art and as would fall withinthe scope of the claims.

In thefdrawings: Y

Fig. 1 is a vertical section of a clipper' partly in elevation embodyingmy invention:

Fig. 2 is a top plan view partly in section of said clipper, a portionof the cover being broken away;

Fig. 3 is a section taken substantially on the line 8-3 of Fig. 2; and

Fig. 4 is a plan view of the core.

Referring in detail to the drawings, my improved clipper constructioncomprises a casing 10 having the cover 11` said casing having thestationary clipper blade 12 secured thereto. Cooperating with thcstationary clipper blade 12 is a movable clipper blade 13 thatreciprocates transversely of the blade 12. The connecting bracket 14forming a part of the movable element of .armature 15 which taperingportion 21 of a core having a cross member 22 thereon extendingtransversely of said coil 2O at one end of the core 21 and 4 terminatingin ears 23 extending on opposite sides of the coil 20 through which'thesecuring devices 211 extend for 'securing the core in position in thecasing 10.-

It Will be noted that the ears 23 forming the ends of the core atopposite sides of the the connecting portionA coil 2O extend toward 1Gand the inward offset 25 in the member 15 to thus provide a path for themagnetic flux that has but a very small amount of air gap. It will alsobe notedthat the central core portion 21 isl smaller at the vend thereofremote from the cross Cpiece 22 gradually increasing lin size towar saidcross piece. It will also be noted that the cross piece 22 is of greaterthickness than the central portion 21 so as to provide the proper amountof iron in this portion of the core. The

Vcoil 20 is free to slide axially along the core portion 21 and isprovided with the end members 26 and 27, the end member 27 havingopenings therein for receiving the fingers 28 provided on the end piece29 connected with the coil spring 30, the opposite end of Which isseated Within vided in the hollow screw-threaded adjusting nut 32 whichscrew-threadedly engages With a screw-threaded opening 33 in the casing10. The member r27 is preferably provided with an ear 34 dependingtherefrom with which the member 29 engages. The adjusting nut 32- may beknurled Vif desired and extends outwardlyV from the casing, as clearlyshown in Figs. 2 and 3 so that adjustment of the same can be made fromoutside the casing 10 vvithout removing the cover 11. The spring 30 is acompression spring and it Will be obvious that by turning in thescrew-threaded member 32, the tension of the'spring 30 can be increasedand vice versa. The spring 30 resists the movement of the coil member 20toward the end of the core 21 that is provided with the cross piece 22.v

When an increase in the voltage occurs, the coil 20 will tend to move onthe core toward the cross piece 22 thereon. The spring 30 will tend toresist such movement and it 17 that is clamped to the.

the bore 31 pro! Will be evident by proper adjustment of the springresistance that such movement can be regulated so that the movement Willbe in such proportion to the increase in voltage that the increase inself-inductance due to the approach of the coil 20 to the cross member22 will counter-balance the effect of the increase in voltage so'thatthe power of the electro-magnet exerted on the vibratory member will besubstantially uniform, thusY avoiding any variation in the operation ofthe movable clipper blade due to the changes in voltage. By taperingthel portion 21 of the core, the coil 20 will tend to center itself asit moves toward the cross piece 22, and the mass of the same alsoincreases progressively towardthe cross piece 22.

Having thus described my invention, what I desire to claim and secure byUnited States Letters Patent is: i

1. In a device of the character described, an electro-magnet comprisinga coil, a core extending through the same, said core having a relativelylarge mass of iron at one end thereof and an armature contacting face atthe other end thereof and said coil being movable on said core towardand away from said mass thereof, and adjustable means for yieldinglyurging said coil away from said .Y

mass.

2. In a device of the character described, av frame, an electro-magnetcomprising a coil, a core extending through the coil and fixed to saidframe, said core having a relatively large mass of iron at one endthereof and said coil being movable on said core toward and away fromsaid end thereof, whereby an increase said coil toward said end of saidcore, resilient means yieldingly resisting said movement, and means onsaid frame for adj usting the tension of said resilient means.

`3. AIn a device of the character described, a core having a contactface at one end thereof and an enlarged transversely extending portionat the other end thereof, an armature Imovable toward and away from saidcontactface, a coil en said core movable Aendvvise thereof and resilientmeans pressing said coil toward said armature.

4:. In a device of the character described, a core having 'a contactface at one end thereof and an enlarged transversely extending portionat the other end thereof, an armature movable toward and away from saidcontact face, a coil on said core movable within fixed limits endwisethereof, resilient means pressing said coil toward said armature andmeans for varying the pressure of said resilient-means against saidcoil.

In Witness whereof, I hereunto subscribe my name this 1st day of Oct.,A. D. 1925.

' LEO J. WAHL.

in voltage tends to move

